The external thrustbelt of Albania consists of some tectonic zones(Ionian,Kruja and Krasta-Cukali zones),that are westward overthrust,with a large amplitude(50e100 km),above the Apulian platform and South Adriatic Bas...The external thrustbelt of Albania consists of some tectonic zones(Ionian,Kruja and Krasta-Cukali zones),that are westward overthrust,with a large amplitude(50e100 km),above the Apulian platform and South Adriatic Basin.The relative movement of the Adriatico-Apulian sub-plate between,the Euro Asiatic and African plates during from the Mesozoic to the Tertiary period,mainly controlled the tectonic evolution of the Albanides.The Ionian zone consists of anticline belts(Berati,Kurveleshi and Cika),that are overthrust toward the west with an amplitude about 20e30 km Their overthrustings was realized through regional sliding evaporitic horizons,which caused the masking of folded structures in the subthrust,with the perspective plays.The Kurveleshi anticlinal belt represents a mega-anticlinal with a length of 210 km and a width of about 20 km,and it is characterized by anticline structures with heterogeneous dimensions,predominantly those of great dimensions and linear type.The overthrusting of the anticline units has a local character,and it is more developed in the Kurveleshi anticlinal belt.Its magnitude is about 8e10 km.As a result of these overthrusts,imbrication and duplex styles are formed,leadind to the masking of the subthrust complex with structures of large interest(e.g.Delvina,Karbunara,etc.)where two oil fields have been dioscovered beneath the Mali Gjere anticline(Delvina oil field)and the Kremenara anticline(Karbunara oil field).Backthrust faults phenomena are secondary and they taken place in the post-collision stage.Generally they are easterward thrust faults of structural units with an amplitude of 5e10 km.The Kurveleshi anticlinal belt,based on tectonic features,is divided into two parts:The southern part,from Qafa Sevaster in the north down to Greece to the south.and northern part,from Qafa Sevaster in the south up to the end of the Patos-Verbas structure.In the southern part these features predominate:The anticline structures are large in size,and overthrust with a large amplitude(8e10 km)westward.The evaporitic diapirs have erupted through local faults of the anticline structures of the Kurveleshi anticlinal belt(Mali Gjere,Kurveleshi and Fterra anticlines).These eruptions(Delvina,Picar-Kapariel-Bashaj,etc.)have helped in the overthrusting of these structural units.It must be mentioned that the backthrusting is also affected by the diapir action.Moreover,vertical diapir occur,in the center of the structures like Navarica.In the northern part,the anticline structures are generally small to medium in size.Only the Patos-Verbas anticline is larger in size.In the Kurveleshi anticlinal belt the Ballsh and Visoka oilfields have developed.The eastern flank of the Shushica synclinal belt apears folded,and the carbonate anticline structures have developed.Existing oil fields include the Gorisht-Kocul,Cakran-Moallaj-Kreshpan and Amonica.These oil fields shoud continue towards the north(under the overthrust of the Patos-Verbas antcline)and in the south(under the regional ovethrust of the Kuervelesh anticlinal belt).展开更多
The Paleogene geological framework and evolution process in the central anticline zone in the Lufeng 13 sag in Pearl River Mouth Basin is well analyzed through seismic data and drilling data,and control of tectonic ev...The Paleogene geological framework and evolution process in the central anticline zone in the Lufeng 13 sag in Pearl River Mouth Basin is well analyzed through seismic data and drilling data,and control of tectonic evolution on hydrocarbon accumulation is also discussed.The results show that the central anticline zone in the Lufeng 13 sag develops the upper deformation layer and lower deformation layer.The“arched graben system”is developed in the upper deformation layer,and the magmatic diapir structure and flowing deformation of plastic strata is developed in the lower deformation layer.The evolution process of the central anticline zone can be divided into four stages,i.e.fault block uplifting stage,prototype stage,strengthening stage and finalization stage.The geological framework and tectonic evolution of the central anticline zone control Paleogene hydrocarbon accumulation.The Paleogene twolayer geological framework is favorable for development of structural traps and composite traps;the paleostructure highs are the direction of hydrocarbon migration,and the gravitational gliding faults are the main carrier bed for vertical hydrocarbon migration;the tectonic uplift is a key factor for reservoir diagenesis improvement and preservation of primary pores,and also controls distribution of high-quality reservoirs.展开更多
From the mid-1800s to the present, the philosophy of oil and gas exploration has had three major breakthroughs. The first breakthrough—from oil seepage to the anticlinal theory; The second breakthrough—from the anti...From the mid-1800s to the present, the philosophy of oil and gas exploration has had three major breakthroughs. The first breakthrough—from oil seepage to the anticlinal theory; The second breakthrough—from the anticlinal theory to the trap theory; The third breakthrough—from the trap theory to the petroleum system. The philosophy of oil finding promotes the petroleum geosciences and exploration technology.展开更多
Based on an elaboration of the resource potential and annual production of tight sandstone gas and shale gas in the United States and China,this paper reviews the researches on the distribution of tight sandstone gas ...Based on an elaboration of the resource potential and annual production of tight sandstone gas and shale gas in the United States and China,this paper reviews the researches on the distribution of tight sandstone gas and shale gas reservoirs,and analyzes the distribution characteristics and genetic types of tight sandstone gas reservoirs.In the United States,the proportion of tight sandstone gas in the total gas production declined from 20%-35%in 2008 to about 8%in 2023,and the shale gas production was 8310×10^(8)m^(3)in 2023,about 80%of the total gas production,in contrast to the range of 5%-17%during 2000-2008.In China,the proportion of tight sandstone gas in the total gas production increased from 16%in 2010 to 28%or higher in 2023.China began to produce shale gas in 2012,with the production reaching 250×10^(8)m^(3)in 2023,about 11%of the total gas production of the country.The distribution of shale gas reservoirs is continuous.According to the fault presence,fault displacement and gas layer thickness,the continuous shale gas reservoirs can be divided into two types:continuity and intermittency.Most previous studies believed that both tight sandstone gas reservoirs and shale gas reservoirs are continuous,but this paper holds that the distribution of tight sandstone gas reservoirs is not continuous.According to the trap types,tight sandstone gas reservoirs can be divided into lithologic,anticlinal,and synclinal reservoirs.The tight sandstone gas is coal-derived in typical basins in China and Egypt,but oil-type gas in typical basins in the United States and Oman.展开更多
SHRIMP zircon U-Pb dating of the Neoproterozoic Maoping （茅坪） series （Sandouping （三斗坪） rock suite） granites exposed in the southern part of the Huangling （黄陵） anticline shows that the formation time of S...SHRIMP zircon U-Pb dating of the Neoproterozoic Maoping （茅坪） series （Sandouping （三斗坪） rock suite） granites exposed in the southern part of the Huangling （黄陵） anticline shows that the formation time of Sandouping biotite-hornblende tonalite intrusion, Jinpansi （金盘寺） hornblende-biotite tonalite intrusion, and Longtanping （龙潭坪） monzogranite are 863±9, 842±10, and 844±10 Ma, respectively. Their geochemical features include A/CNK=0.98-1.06, from metaluminous to weakly peraluminous, δ=1.37-1.53, Sm/Nd=0.17-0.24, and RbN/YbN=1.1-3.62. These indicate that the granite rocks are supersaturated SiO2 calc-alkaline granitoids. The characteristic of Sr-Nd isotopic composition is that the values of εNd（t） and εsr（t） are -12.4 to -11.0 and 20.2-32.2, respectively. It also suggests that the material source of the granite rocks mainly originated from the crust, and they formed in a volcanic arc tectonic environment. These facts suggest that the occurrence of Neoproterozoic granitoids in the southern part of the Huangling anticline should be related to an arc environment along an active continental margin caused by southward subduction of oceanic crust beneath the northern Yangtze craton, and the formation age is not later than 863 Ma.展开更多
The olivine-gabbroic rocks located at the Huangiing anticline within the Yangtze Craton are dated at circa 857-854 Ma by LA-ICP-MS method. The rocks belong to the sub-alkaline series and consist of pyroxene （35%-40%...The olivine-gabbroic rocks located at the Huangiing anticline within the Yangtze Craton are dated at circa 857-854 Ma by LA-ICP-MS method. The rocks belong to the sub-alkaline series and consist of pyroxene （35%-40%）, plagioclase （40% -45%）, olivine （8%-10%） and spinel （3%-5%）. Olivine has Fo values of 73-83 that is classified as chrysolite. Pyroxene has relative low contents of FeO （6.60 wt.%-8.23 wt.%） but high CaO （20.23 wt.%-21.25 wt.%） contents, however, plagioclase has high A1203 （31.78 wt.%o-32.37 wt.%）, CaO （16.08 wt.%-16.25 wt.%） and An （79-80） values, but low Na20 contents （1.95 wt.%-2.11 wt.%）. Spinel are magnesioferrite with characteristics of high contents of MgO （13.65 wt.%- 13.68 wt.%）, FeO （23.27 wt.%-23.40 wt.%） and A1203 （62.43 wt.%-62.74 wt.%）. Chemical compositions of these minerals are similar to those of gabbro rocks that were formed in the post-orogeny environment. The olivine-gabbro samples have negative zircon eHf values （-16.57±0.47） that resemble the mafic rocks in the same region, indicating that they are derived from the extremely enriched mantle source. On the compilation of documented Neoproterozoic mafic rocks in the Yangtze Craton, it is proposed that the mantle in the northern Yangtze Craton has experienced different degrees enrichment during the Neoproterozoic.展开更多
In January 2010, the Suining Ms5.0 earthquake occurred in central Sichuan Basin, with the epicenter in Moxi-Longnvsi structural belt and a focal depth of 10 km. Based on structural interpretations of seismic profiles ...In January 2010, the Suining Ms5.0 earthquake occurred in central Sichuan Basin, with the epicenter in Moxi-Longnvsi structural belt and a focal depth of 10 km. Based on structural interpretations of seismic profiles in this area, we recognized a regional detachment fault located at a depth of 9-10 km in the Presinian basement of the Suining area, transferring its slipping from NW to SE orientation. This detachment fault slipped from NW to SE, and underwent several shears and bends, which caused the basement to be rolled in and the overlaying strata fold deformation. It formed a fault-bend fold in the Moxi area with an approximate slip of 4 km. Correspondingly, the formation of the Moxi anticline is related to the detachment fault. With the earthquake＇s epicenter on the ramp of the detachment fault, there is a new point of view that the Suining earthquake was caused by re-activation of this basement detachment fault. Since the Late Jurassic period, under the influence of regional tectonic stress, the detachment fault transfered its slip from the Longmen Mountains （LMS） thrust belt to the hinterland of the Sichuan Basin, and finally to the piedmont zone of southwest Huayingshan （HYS）, which indicates that HYS might be the final front area of the LMS thrust belt.展开更多
The stratigraphic, structural and metamorphic features of the basal thrust belt of the ca. 1.0 Ga Miaowan （庙湾） ophiolite in the southern Huangling （黄陵） anticline, show that it can be divided into three tectono...The stratigraphic, structural and metamorphic features of the basal thrust belt of the ca. 1.0 Ga Miaowan （庙湾） ophiolite in the southern Huangling （黄陵） anticline, show that it can be divided into three tectono-lithostratigraphic units from north to south： mélange/wildflysch rock units, flysch rock units, and sedimentary rock units of the autochthonous （in situ） stable continental margin. The three units underwent thrust-related deformation during emplacement of the Miaowan ophiolitic nappe, with kinematic indicators indicating movement from the NNE to SSW, with the metamorphic grade reaching greenschist-amphibolite facies. LA-ICP-MS U-Pb geochronology of zircons from granite pebbles in the basal thrust-related wildflysch yield ages of 859±26, 861＋12 and 871±16 Ma; whereas monzonitic granite clasts yield an age of 813±14 Ma. This indicates that the formation age of the basal thrust belt is not older than 813±14 Ma, and is earlier than the earliest formation time of the majority of the Neoproterozoic Huangling granitoid intrusive complex, which did not experience penetrative ductile deforma-tion. These results suggest that the northern margin of the Yangtze craton was involved in collisional tectonics that continued past 813 Ma.This may be related to the amalgamation of the Yangtze craton with the Rodinia supercontinent. Through comparative study of lithology, zircon geochronology, REE patterns between granodiorite and tonalite pebbles in the basal thrust-zone conglomerate, it can be concluded that the pebbles are the most similar to the Huanglingmiao （黄陵庙） rock-mass （unit）, implying that they may have come from Huanglingmiao rock-mass. Zircon cores yield xenocrystic ages of 2 074±120 Ma, suggesting that the protolith of the Neoproterozoic Huangling granitoid intrusive complex may have originated from par-tial melting of older basement rocks, that is to say there may be Paleoproterozoic crystalline basement in the southern Huangling anticline. The ages of xenocrystic zircons in the granite pebbles in the basal-thrust congiomerate/wildflysch show a correlation with the age spectra from Australia, implying that the terrain that collided with the northern margin of the Yangtze craton and emplaced the Miaowan ophiolite at ca. 813 Ma may have been derived from the Australian segment of Rodinia.展开更多
We report preliminary results of a geochemical study on banded iron formations （BIFs） in the Zhaojiayangpo （赵家阳坡） area from the Kongling （崆岭） Group in the northern Huangling （黄陵） anticline, on the nort...We report preliminary results of a geochemical study on banded iron formations （BIFs） in the Zhaojiayangpo （赵家阳坡） area from the Kongling （崆岭） Group in the northern Huangling （黄陵） anticline, on the northern margin of the Yangtze craton. The CL （cathodoluminescence） images of zircons mostly have sector zoning, fir-tree zoning and patched zoning, and a few show core-rim tex-tures with rims having patched zoning. The calculated formation temperatures using the Ti-in-zircon thermometer are 660-808 ℃ （714 ℃C in aver-age）, all indicating that the BIFs underwent granulite facies metamorphism. The age of zir-cons with granulite facies metamorphism is 1 990±14 Ma by LA-ICP-MS U-Pb dating, indi-cating that there was a significant granulite fa-cies tectonothermal event in the northern Huangling anticline in the Paleoproterozoic, which may be related with tectonic thermal events of the metamorphism caused by the as-sembly of the Columbia supercontinent with South China. Moreover, the REE pattern ischaracterized by depletion in LREE while relatively flat in HREE, LaN/YbN=0.26, with a positive Eu anomaly （Eu/Eu^＊---1.59）, which reveals its hydrothermal sedimentation origin and it may have formed in the environment of submarine exhalation.展开更多
Based on exploration and development results and evaluation of marine shale gas in South China in the past ten years, in view of the features of "high maturity, strong tectonic reformation and high shear stress&q...Based on exploration and development results and evaluation of marine shale gas in South China in the past ten years, in view of the features of "high maturity, strong tectonic reformation and high shear stress" of the shale in Zhaotong exploration zone in the Yunnan and Guizhou Plateau, as well as the key issues of long time diffusion and leakage of shallow shale gas, and the preservation conditions, the factors controlling shallow shale gas sweet spot and key zone selection evaluation technology of shale gas are investigated. From 2017 to 2018, the first significant exploration breakthrough was made in the Taiyang anticline at a buried depth of 700 to 2 000 m, discovering large-scale proved geological reserves of shallow shale gas. By examining the accumulation conditions and sweet spot control factors of the shallow shale gas in this area, it is found that the accumulation and productivity potential of shale gas in the mountainous area with complex structure outside basin are controlled by five factors:(1) The gas-rich area has weak tectonic reformation and good preservation conditions on the whole, taking on typical anticline trap occurrence mode.(2) The gas-rich area is in over-pressure state and high in shale gas content.(3) The gas-rich area has high quality shale and thus superior source rock condition.(4) The gas-rich area has high quality reservoirs dominated by class I.(5) The shale gas reservoir in the gas-rich area has high content of brittle minerals and small difference between maximum and minimum horizontal stresses which are conducive to hydraulic fracturing. The innovative practice and core technologies formed during the exploration and production capacity construction of shallow shale gas in the Zhaotong demonstration zone have great reference significance for shallow shale gas exploration and development in other areas.展开更多
ABSTRACT： Yinger sag is the main petroleum and only the Changshaling oil resource has shaling anticline crest zone was formed above the generative sag in eastern Jiuquau Basin, been found after 60 years prospectin...ABSTRACT： Yinger sag is the main petroleum and only the Changshaling oil resource has shaling anticline crest zone was formed above the generative sag in eastern Jiuquau Basin, been found after 60 years prospecting. Chang- regional uplift, and was slightly affected by crest was identified as a structural transposition zone. Based on analysis of seismic facies, logging facies and seismic inversion technique, it has been demonstrated that anticline crest zone conducts drainage entering basin and dominates sedimentary detritus further dispersing, and the anticline crest zone controls the distribution of sand bodies and the development of sedimentary system consequently. The sequence stratigraphic patterns of multi-step fault belt in Member 3 of Xiagou Formation in Lower Cretaceous in the anticline crest zone is composed of the development of sedimentary facies in plan and distribution of multi-step fault belt sand bodies in spa- tial. This research investigates the sand-control models and sequence patterns, and finally a model of reservoirs in anticline crest zone is identified.展开更多
In this study,we aim to clarify the structural characteristics and deformation process of the Changning anticline.We carefully interpret 38 two-dimensional(2D)seismic profiles in the study area and establish three-dim...In this study,we aim to clarify the structural characteristics and deformation process of the Changning anticline.We carefully interpret 38 two-dimensional(2D)seismic profiles in the study area and establish three-dimensional(3D)geometric and quantitative kinematic models of the Changning anticline.This study shows that the basement fault controls the formation of the Changning anticline.The fault slope of the main fault in the basement shows’steep in the upper and gentle in the lower’structural characteristics vertically,possessing obvious segmentary characteristics transversely and presents the overall characteristics of’steep in the east and gentle in the west’.Further analysis shows that the Changning anticline proceeds west and terminates at the boundary defined by current surface features but gradually disappears westward across the Mt.Huaying fault zone.Furthermore,we identified that deformation of the Changning anticline began during the early Yanshanian movement period.Under compressional stress from the southeast,the anticline slid forward along the basement fault until the end of the Yanshanian movement period,when the dominant WNW-ESE structure gradually emerged.Since the Himalayan movement period,a series of NE-trending structures have been formed in the anticline,owing to multi-directional compressive stress.展开更多
The study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin (175 km from Persian Gulf). The Zagros fold-thrust belt is home to one of the largest petroleum producing reservoir...The study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin (175 km from Persian Gulf). The Zagros fold-thrust belt is home to one of the largest petroleum producing reservoirs in the world. Structures in this area have complications and the study anticline has unique structures in the Fars region. In the study area, the Kuh-e Qazi anticline due to special fold style and rotation toward Northeast is the unique structure between anticlines of the Zagros belt. This anticline is fault bend fold and plunge of the anticline in eastern part rotated toward Northeast along with the Nezamabad fault trend. In this area, the Kuh-e Qazi anticline has asymmetric structures and some faults such as the Nezamabad and the Sarvestan strike slip fault effect on this anticline. The geometry of anticlines in the Zagros fold-thrust belt is affected by the type of deformation and mechanical behavior of stratigraphic units specially detachment units. The purpose of this research is to determine of folding pattern of the Kuh-e Qazi anticline and define structural features affected on them in the study area. This paper presents a part of the results of a regional study of the Fars province in the Zagros Simply Folded Belt, based on original fieldwork, satellite images, structural sections, geological maps and well data. Also, we use some software as Global Mapper and Tectonics FP for preparing some data.?Based on the research, which have been done, the boundary between ductile and frictional substrates causes rotation as a result of lateral, along-strike migration of the ductile substrate. The ductile or viscose layer in the study area is Hormuz Series. Due to lack or thinning of Hormuz salt over the Gavbandi basement high and in the eastern side of the Nezamabad basement fault, causes translation of strain and anticlockwise rotation in Southeast of the Kuh-e Qazi anticline toward Northwest unlike foreland basin due to the Nezamabad fault activity. This style between all of the anticlines in the study area is unique that rotates unlike foreland basin. In addition, influence on anticlockwise rotation, extensional stress has been created and then salt dome cropping out in Southeast of the Kuh-Qazi anticline. One of the best evidence for effect of extensional stress is triangular facets in this part of the study anticline. Based on folding analysis (geometry of axial plane and fold orientation), it is clearly confirmed that the translation of strain and anticlockwise rotation in Southeast of the Kuh-e Qazi anticline toward Northwest has been formed by basement fault activity as the Nezamabad fault in the boundary between ductile and frictional substrates of the study area.展开更多
The main area of the Jiaoshiba anticline of the Fuling shale gas field was taken as the research object,laboratory rock mechanical experiments and direct shear experiments were conducted to clarify the mechanical anis...The main area of the Jiaoshiba anticline of the Fuling shale gas field was taken as the research object,laboratory rock mechanical experiments and direct shear experiments were conducted to clarify the mechanical anisotropy characteristics and parameters of rock samples with rich beddings.Based on the experimental results,a 3D fracture propagation model of the target reservoir taking mechanical anisotropy,weak bedding plane and vertical stress difference into account was established by the discrete element method to analyze distribution patterns of hydraulic fractures under different bedding densities,mechanical properties,and fracturing engineering parameters(including perforation clusters,injection rates and fracturing fluid viscosity).The research results show that considering the influence of the weak bedding plane and longitudinal stress difference,the interlayer stress difference 3–4 MPa in the study area can control the fracture height within the zone of stress barrier,and the fracture height is less than 40 m.If the influence of the weak bedding plane is not considered,the simulation result of fracture height is obviously higher.Although the opening of high-density bedding fractures increases the complexity of hydraulic fractures,it significantly limited the propagation of fracture height.By reducing the number of clusters,increasing the injection rate,and increasing the volume and proportion of high-viscosity fracturing fluid in the pad stage,the restriction on fracture height due to the bedding plane and vertical stress difference can be reduced,and the longitudinal propagation of fractures can be promoted.The fracture propagation model was used to simulate one stage of Well A in Fuling shale gas field,and the simulation results were consistent with the micro-seismic monitoring results.展开更多
Hydraulic fracturing is a key technology in shale gas extraction,whether hydraulic fracturing induces earthquakes has become a hot topic in the public and the focus of scholars’research.The urgency of shale gas minin...Hydraulic fracturing is a key technology in shale gas extraction,whether hydraulic fracturing induces earthquakes has become a hot topic in the public and the focus of scholars’research.The urgency of shale gas mining and the catastrophic nature of earthquakes highlight the urgent need to study this issue.The Changning anticline at the southern margin of the Sichuan Basin is a key area for shale gas exploitation.Taking this as an example,this paper applies the velocity model of the study area to reposition the M5.7 magnitude earthquake on December 16,2018 and the M5.3 magnitude earthquake on January 03,2019 and their aftershock sequence in this area.Using shale gas exploration drilling and reflection seismic data to carry out structural analysis,and recovering the tectonic geological setting of earthquake occurrence by restoring the formation process of the Changning anticline,to further explore the seismic mechanism.Our results show that the Changning anticline is a large basement fault-bend fold,and the displacement of the fault forming the anticline is 18 km,and the Changning anticline absorbs 33%of the fault slip.The Silurian Longmaxi Formation of the Changning anticline experienced larger-parallel shearing along underlying basement faults,forming a micro-fracture system.The footwall ramp of the basement fault is reactivated at present,earthquakes in this area mostly occur along the footwall ramp of the basement fault and above and below it.The anticlinal and synclinal hinge zones are also the earthquake concentration areas,but the earthquake magnitude decreases upwards along the kink-band,and small earthquakes below M2.0 occur in the Silurian Longmaxi Formation.So far,the earthquake in the Changning anticline mainly occurred in the southern limb of the anticline,which is a natural earthquake formed along the footwall ramp of the basement fault.The earthquakes in the Changning area are possible related to the geo-tectonic setting for the southeast outward compression of the Qinghai-Tibet Plateau at present,the moderate or large-scale earthquakes in the southwest Sichuan Basin are mainly due to the reactivation during late Quaternary of the earlier formed faults.It is suggested to carry out scientific monitoring of seismic activities in shale gas development zones.展开更多
The Kuh-e Siah anticline is located in the Sarvestan area of the Fars province (186 km to Persian Gulf) and Interior Fars sub basin. This anticline is a fault bend fold and is located in the Sarvestan fault zone with ...The Kuh-e Siah anticline is located in the Sarvestan area of the Fars province (186 km to Persian Gulf) and Interior Fars sub basin. This anticline is a fault bend fold and is located in the Sarvestan fault zone with Northwest-Southeast trend. The Sarvestan fault zone has caused main deformation by dextral strike slip activity in southern part of the Zagros fold-thrust belt. The main aim of this paper is to determine of fold style elements and folding pattern of the Kuh-e Siah anticline. This paper presents part of the results of a regional study of the Fars province in the Zagros Simply folded belt, based on original fieldwork, satellite images, structural sections, geological maps and well data. In addition, we used some software as Global Mapper and Tectonics FP for prepared some data. Folds, which are close sideways, are neutral and these require special attention. It is remarkable that, in all sections of the Kuh-e Siah anticline, fold type is close and in the middle part of the anticline, fold type is different with other parts. In the middle part, fold type is upright-moderately gently plunging. On the other hand, in northwestern and southeastern parts fold type is similar together. These results maybe show that fold style follow that fold sigmoidal shape that created with two-fault segment of the Sarvestan fault zone in the study area. Therefore, it seems that the Kuh-e Siah anticline has suffered high deformation in the Sarvestan fault zone and this fault zone has created shear zone.展开更多
The Study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin. The Khaftar anticline is located in the West, North-West of Jahrom city in the Fars province (148 km distance from...The Study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin. The Khaftar anticline is located in the West, North-West of Jahrom city in the Fars province (148 km distance from Persian Gulf). The trend of Khaftar anticline has three orientations, consist of North-Northeast, East-West and South-Southwest. This anticline has asymmetric structure and some faults with large strike separation observed in this anticline. In the study area, stratigraphic units are affected by many faults in this area. Also one salt plug cropping out in the middle part of the Khaftar anticline. Maybe this salt plug affected on the stratigraphic units and geometry of structure. Description of fold geometry is important because it allows comparisons within and between folds and allow us to recognize patterns in the occurrence and distribution of fold systems. The main aim of this paper is determination of fold style elements and folding pattern of the Khaftar anticline. This paper presents a part of the results of a regional study of the Fars province in the Zagros Simply folded belt, based on satellite images, geological maps, and well data. Some data, such as geological maps and geological regional data were prepared and provided by the National Iranian Oil Company (NIOC). Because of the Khaftar anticline, has complex structure, the analysis of fold style elements is seems necessary. Therefore, in further studies on this structure the changes of fold style elements will be analyzed and investigated from east to west in the different parts of this anticline. The activity of Nezamabad sinistral strike slip fault in the Khaftar anticline causes changes of axial plane characteristics and fold axis. Some of the results such as folding style analysis, how position of salt plug, changes of fold type and main structural changes (rotation of fold axis and 2.5 km displacement in this anticline) show main changes in the middle parts of the Khaftar anticline. It seems that, these changes have formed by activity of the Nezamabad fault and this fault’s activity same as fault zone.展开更多
The Khalfani anticline is located in the Coastal Fars (Zagros, adjacent Persian Gulf). This anticline with Northwest-Southeast trend is a fault bend fold. In the study area, the Khalfani anticline has increased elevat...The Khalfani anticline is located in the Coastal Fars (Zagros, adjacent Persian Gulf). This anticline with Northwest-Southeast trend is a fault bend fold. In the study area, the Khalfani anticline has increased elevation from West to East with three distinct humps. The major faults in the study area are the Hendurabi and the Razak sinistral strike slip faults. Because analysis of fold and their folding styles in different parts system is important, the analysis of folding style elements is necessary for structural studies. The main aim of this research is structural style analysis based on fold style elements in the Khalfani anticline. This analysis is important for progress in hydrocarbons exploration in the Coastal Fars area. In this research, we used Tectonics FP and Global Mapper Software for preparing some data in our study. In addition, we used the common classification of folds for our research. Based on given results, the folding pattern of this anticline has indicated that the fold style is same in different parts of the Khalfani anticline. In the study area, based on classifications of fold in different methods, fold style is same together. Fold, with close sideways requires special attention as structural view;then the Khalfani Anticline with close style in all parts has special deformation and folding style. It seems that in the study area, folding style and variation of structural style have been created by effect of the Razak and the Hendurabi sinistral strike slip fault. Because these faults are basement or deep-seated faults, special folding style and special deformation can be formed in the study area. In addition, the Khalfani anticline in the study area has restricted within the Razak and the Hendurabi sinistral strike slip faults.展开更多
The Gavbast anticline is located in the Coastal Fars area of the Zagros folded belt, with north-south trend. The study anticline is restricted to the Bavush and Paskhand anticlines from North, the Gezzeh and Dehnow an...The Gavbast anticline is located in the Coastal Fars area of the Zagros folded belt, with north-south trend. The study anticline is restricted to the Bavush and Paskhand anticlines from North, the Gezzeh and Dehnow anticlines from South, the Varavi anticline from West and Nakh anticline from East (Figure 1). Description of fold geometry is important because they allow comparisons within and between folds and pattern-recognition in addition to occurrence and distribution of fold systems. The main goal of this paper is to define folding style of the Gavbast anticline and define structural features affected on them in the study area. In this research, we used the Tectonics FP software, Global Mapper software and geological maps and reports of Iranian National Oil Company. In addition, we used common classification of fold for indicating of folding mechanism of the Tabnak anticlinal structure. In the Gavbast anticline, fold style elements in all parts of this anticline have been calculated and analyzed for indicating of folding style mechanism. The results of this method have been shown the folding geometry changes accurately. The Gavbast anticline is gentle in structural sections D-D' and G-G' to K-K'. The anticline is an open fold in the L-L' section. Also fold type in the E-E' and F-F' sections of the Gavbast anticline is steeply inclined sub-horizontal. These sections are located between the Razak (western part) and Hendurabi fault (eastern part). It seems that E-E' and F-F' parts in the Gavbast anticline have been suffered most deformation affected by the Razak and Hendurabi faults. At the end of, it seems that, the Razak and Hendurabi faults have major effects on folding style. This structure is a very good sample for effect of strike slip faults on the folding geometry and for this reason;the Gavbast anticline is considered a special structural style in the Zagros fold-thrust Belt.展开更多
Objectives Important clues have been found for potassium prospecting in the Huangjinkou anticline of the northeast Sichuan Basin in the 1970s(Zheng et al.,2015;Lin et al.,2004).In 2008,China Geological Survey launched...Objectives Important clues have been found for potassium prospecting in the Huangjinkou anticline of the northeast Sichuan Basin in the 1970s(Zheng et al.,2015;Lin et al.,2004).In 2008,China Geological Survey launched a prospective investigation of potash resources in the western region of China,and the local governments and private-owned enterprises also responded positively.Then,展开更多
文摘The external thrustbelt of Albania consists of some tectonic zones(Ionian,Kruja and Krasta-Cukali zones),that are westward overthrust,with a large amplitude(50e100 km),above the Apulian platform and South Adriatic Basin.The relative movement of the Adriatico-Apulian sub-plate between,the Euro Asiatic and African plates during from the Mesozoic to the Tertiary period,mainly controlled the tectonic evolution of the Albanides.The Ionian zone consists of anticline belts(Berati,Kurveleshi and Cika),that are overthrust toward the west with an amplitude about 20e30 km Their overthrustings was realized through regional sliding evaporitic horizons,which caused the masking of folded structures in the subthrust,with the perspective plays.The Kurveleshi anticlinal belt represents a mega-anticlinal with a length of 210 km and a width of about 20 km,and it is characterized by anticline structures with heterogeneous dimensions,predominantly those of great dimensions and linear type.The overthrusting of the anticline units has a local character,and it is more developed in the Kurveleshi anticlinal belt.Its magnitude is about 8e10 km.As a result of these overthrusts,imbrication and duplex styles are formed,leadind to the masking of the subthrust complex with structures of large interest(e.g.Delvina,Karbunara,etc.)where two oil fields have been dioscovered beneath the Mali Gjere anticline(Delvina oil field)and the Kremenara anticline(Karbunara oil field).Backthrust faults phenomena are secondary and they taken place in the post-collision stage.Generally they are easterward thrust faults of structural units with an amplitude of 5e10 km.The Kurveleshi anticlinal belt,based on tectonic features,is divided into two parts:The southern part,from Qafa Sevaster in the north down to Greece to the south.and northern part,from Qafa Sevaster in the south up to the end of the Patos-Verbas structure.In the southern part these features predominate:The anticline structures are large in size,and overthrust with a large amplitude(8e10 km)westward.The evaporitic diapirs have erupted through local faults of the anticline structures of the Kurveleshi anticlinal belt(Mali Gjere,Kurveleshi and Fterra anticlines).These eruptions(Delvina,Picar-Kapariel-Bashaj,etc.)have helped in the overthrusting of these structural units.It must be mentioned that the backthrusting is also affected by the diapir action.Moreover,vertical diapir occur,in the center of the structures like Navarica.In the northern part,the anticline structures are generally small to medium in size.Only the Patos-Verbas anticline is larger in size.In the Kurveleshi anticlinal belt the Ballsh and Visoka oilfields have developed.The eastern flank of the Shushica synclinal belt apears folded,and the carbonate anticline structures have developed.Existing oil fields include the Gorisht-Kocul,Cakran-Moallaj-Kreshpan and Amonica.These oil fields shoud continue towards the north(under the overthrust of the Patos-Verbas antcline)and in the south(under the regional ovethrust of the Kuervelesh anticlinal belt).
基金supported by the National Science and Technology Major Project of China(No.2016ZX05024-004)comprehensive scientific research project of CNOOC(China National Offshore Oil Corporation)(YXKY-2015-SZ-02).
文摘The Paleogene geological framework and evolution process in the central anticline zone in the Lufeng 13 sag in Pearl River Mouth Basin is well analyzed through seismic data and drilling data,and control of tectonic evolution on hydrocarbon accumulation is also discussed.The results show that the central anticline zone in the Lufeng 13 sag develops the upper deformation layer and lower deformation layer.The“arched graben system”is developed in the upper deformation layer,and the magmatic diapir structure and flowing deformation of plastic strata is developed in the lower deformation layer.The evolution process of the central anticline zone can be divided into four stages,i.e.fault block uplifting stage,prototype stage,strengthening stage and finalization stage.The geological framework and tectonic evolution of the central anticline zone control Paleogene hydrocarbon accumulation.The Paleogene twolayer geological framework is favorable for development of structural traps and composite traps;the paleostructure highs are the direction of hydrocarbon migration,and the gravitational gliding faults are the main carrier bed for vertical hydrocarbon migration;the tectonic uplift is a key factor for reservoir diagenesis improvement and preservation of primary pores,and also controls distribution of high-quality reservoirs.
文摘From the mid-1800s to the present, the philosophy of oil and gas exploration has had three major breakthroughs. The first breakthrough—from oil seepage to the anticlinal theory; The second breakthrough—from the anticlinal theory to the trap theory; The third breakthrough—from the trap theory to the petroleum system. The philosophy of oil finding promotes the petroleum geosciences and exploration technology.
基金Supported by the National Key R&D Project(2019YFC1805505)National Natural Science Foundation of China(42272188,42172149,U2244209)+2 种基金Science and Technology Special Project of China National Petroleum Corporation(2023YQX10101)Petrochemical Joint Fund Integration Project of National Natural Science Foundation of China(U20B6001)Shale Gas Academician Workstation Project of Guizhou Energy Industry Research Institute Co.,Ltd.([2021]45-2)。
文摘Based on an elaboration of the resource potential and annual production of tight sandstone gas and shale gas in the United States and China,this paper reviews the researches on the distribution of tight sandstone gas and shale gas reservoirs,and analyzes the distribution characteristics and genetic types of tight sandstone gas reservoirs.In the United States,the proportion of tight sandstone gas in the total gas production declined from 20%-35%in 2008 to about 8%in 2023,and the shale gas production was 8310×10^(8)m^(3)in 2023,about 80%of the total gas production,in contrast to the range of 5%-17%during 2000-2008.In China,the proportion of tight sandstone gas in the total gas production increased from 16%in 2010 to 28%or higher in 2023.China began to produce shale gas in 2012,with the production reaching 250×10^(8)m^(3)in 2023,about 11%of the total gas production of the country.The distribution of shale gas reservoirs is continuous.According to the fault presence,fault displacement and gas layer thickness,the continuous shale gas reservoirs can be divided into two types:continuity and intermittency.Most previous studies believed that both tight sandstone gas reservoirs and shale gas reservoirs are continuous,but this paper holds that the distribution of tight sandstone gas reservoirs is not continuous.According to the trap types,tight sandstone gas reservoirs can be divided into lithologic,anticlinal,and synclinal reservoirs.The tight sandstone gas is coal-derived in typical basins in China and Egypt,but oil-type gas in typical basins in the United States and Oman.
基金supported by the China Geological Survey Project (Nos. 1212010710715 and 1212011085340)
文摘SHRIMP zircon U-Pb dating of the Neoproterozoic Maoping （茅坪） series （Sandouping （三斗坪） rock suite） granites exposed in the southern part of the Huangling （黄陵） anticline shows that the formation time of Sandouping biotite-hornblende tonalite intrusion, Jinpansi （金盘寺） hornblende-biotite tonalite intrusion, and Longtanping （龙潭坪） monzogranite are 863±9, 842±10, and 844±10 Ma, respectively. Their geochemical features include A/CNK=0.98-1.06, from metaluminous to weakly peraluminous, δ=1.37-1.53, Sm/Nd=0.17-0.24, and RbN/YbN=1.1-3.62. These indicate that the granite rocks are supersaturated SiO2 calc-alkaline granitoids. The characteristic of Sr-Nd isotopic composition is that the values of εNd（t） and εsr（t） are -12.4 to -11.0 and 20.2-32.2, respectively. It also suggests that the material source of the granite rocks mainly originated from the crust, and they formed in a volcanic arc tectonic environment. These facts suggest that the occurrence of Neoproterozoic granitoids in the southern part of the Huangling anticline should be related to an arc environment along an active continental margin caused by southward subduction of oceanic crust beneath the northern Yangtze craton, and the formation age is not later than 863 Ma.
基金support by the National Natural Science Foundation of China (No. 41272242)the Education Department of Jiangxi Province (No. GJJ150562)the East China University of Technology (No. DHBK2015321)
文摘The olivine-gabbroic rocks located at the Huangiing anticline within the Yangtze Craton are dated at circa 857-854 Ma by LA-ICP-MS method. The rocks belong to the sub-alkaline series and consist of pyroxene （35%-40%）, plagioclase （40% -45%）, olivine （8%-10%） and spinel （3%-5%）. Olivine has Fo values of 73-83 that is classified as chrysolite. Pyroxene has relative low contents of FeO （6.60 wt.%-8.23 wt.%） but high CaO （20.23 wt.%-21.25 wt.%） contents, however, plagioclase has high A1203 （31.78 wt.%o-32.37 wt.%）, CaO （16.08 wt.%-16.25 wt.%） and An （79-80） values, but low Na20 contents （1.95 wt.%-2.11 wt.%）. Spinel are magnesioferrite with characteristics of high contents of MgO （13.65 wt.%- 13.68 wt.%）, FeO （23.27 wt.%-23.40 wt.%） and A1203 （62.43 wt.%-62.74 wt.%）. Chemical compositions of these minerals are similar to those of gabbro rocks that were formed in the post-orogeny environment. The olivine-gabbro samples have negative zircon eHf values （-16.57±0.47） that resemble the mafic rocks in the same region, indicating that they are derived from the extremely enriched mantle source. On the compilation of documented Neoproterozoic mafic rocks in the Yangtze Craton, it is proposed that the mantle in the northern Yangtze Craton has experienced different degrees enrichment during the Neoproterozoic.
基金support from the National Basic Research Program(No:2006CB202300)National Natural Science Foundation of China(Grant No:40739906)
文摘In January 2010, the Suining Ms5.0 earthquake occurred in central Sichuan Basin, with the epicenter in Moxi-Longnvsi structural belt and a focal depth of 10 km. Based on structural interpretations of seismic profiles in this area, we recognized a regional detachment fault located at a depth of 9-10 km in the Presinian basement of the Suining area, transferring its slipping from NW to SE orientation. This detachment fault slipped from NW to SE, and underwent several shears and bends, which caused the basement to be rolled in and the overlaying strata fold deformation. It formed a fault-bend fold in the Moxi area with an approximate slip of 4 km. Correspondingly, the formation of the Moxi anticline is related to the detachment fault. With the earthquake＇s epicenter on the ramp of the detachment fault, there is a new point of view that the Suining earthquake was caused by re-activation of this basement detachment fault. Since the Late Jurassic period, under the influence of regional tectonic stress, the detachment fault transfered its slip from the Longmen Mountains （LMS） thrust belt to the hinterland of the Sichuan Basin, and finally to the piedmont zone of southwest Huayingshan （HYS）, which indicates that HYS might be the final front area of the LMS thrust belt.
基金supported by the Postdoctoral Science Foundation (No. 20100471203)the Ministry of Land and Resources of China (No. 1212010670104)+1 种基金the National Natural Science Foundation of China (Nos. 91014002, 40821061, 41272242)Ministry of Education of China (Nos. B07039,TGRC201024)
文摘The stratigraphic, structural and metamorphic features of the basal thrust belt of the ca. 1.0 Ga Miaowan （庙湾） ophiolite in the southern Huangling （黄陵） anticline, show that it can be divided into three tectono-lithostratigraphic units from north to south： mélange/wildflysch rock units, flysch rock units, and sedimentary rock units of the autochthonous （in situ） stable continental margin. The three units underwent thrust-related deformation during emplacement of the Miaowan ophiolitic nappe, with kinematic indicators indicating movement from the NNE to SSW, with the metamorphic grade reaching greenschist-amphibolite facies. LA-ICP-MS U-Pb geochronology of zircons from granite pebbles in the basal thrust-related wildflysch yield ages of 859±26, 861＋12 and 871±16 Ma; whereas monzonitic granite clasts yield an age of 813±14 Ma. This indicates that the formation age of the basal thrust belt is not older than 813±14 Ma, and is earlier than the earliest formation time of the majority of the Neoproterozoic Huangling granitoid intrusive complex, which did not experience penetrative ductile deforma-tion. These results suggest that the northern margin of the Yangtze craton was involved in collisional tectonics that continued past 813 Ma.This may be related to the amalgamation of the Yangtze craton with the Rodinia supercontinent. Through comparative study of lithology, zircon geochronology, REE patterns between granodiorite and tonalite pebbles in the basal thrust-zone conglomerate, it can be concluded that the pebbles are the most similar to the Huanglingmiao （黄陵庙） rock-mass （unit）, implying that they may have come from Huanglingmiao rock-mass. Zircon cores yield xenocrystic ages of 2 074±120 Ma, suggesting that the protolith of the Neoproterozoic Huangling granitoid intrusive complex may have originated from par-tial melting of older basement rocks, that is to say there may be Paleoproterozoic crystalline basement in the southern Huangling anticline. The ages of xenocrystic zircons in the granite pebbles in the basal-thrust congiomerate/wildflysch show a correlation with the age spectra from Australia, implying that the terrain that collided with the northern margin of the Yangtze craton and emplaced the Miaowan ophiolite at ca. 813 Ma may have been derived from the Australian segment of Rodinia.
基金supported by the Postdoctoral Science Foundation (No. 20100471203)the Ministry of Land and Resources(No. 1212010670104)+1 种基金the National Natural Science Foundation of China (Nos. 91014002, 40821061, 41272242)Ministry of Education of China (Nos. B07039, TGRC201024)
文摘We report preliminary results of a geochemical study on banded iron formations （BIFs） in the Zhaojiayangpo （赵家阳坡） area from the Kongling （崆岭） Group in the northern Huangling （黄陵） anticline, on the northern margin of the Yangtze craton. The CL （cathodoluminescence） images of zircons mostly have sector zoning, fir-tree zoning and patched zoning, and a few show core-rim tex-tures with rims having patched zoning. The calculated formation temperatures using the Ti-in-zircon thermometer are 660-808 ℃ （714 ℃C in aver-age）, all indicating that the BIFs underwent granulite facies metamorphism. The age of zir-cons with granulite facies metamorphism is 1 990±14 Ma by LA-ICP-MS U-Pb dating, indi-cating that there was a significant granulite fa-cies tectonothermal event in the northern Huangling anticline in the Paleoproterozoic, which may be related with tectonic thermal events of the metamorphism caused by the as-sembly of the Columbia supercontinent with South China. Moreover, the REE pattern ischaracterized by depletion in LREE while relatively flat in HREE, LaN/YbN=0.26, with a positive Eu anomaly （Eu/Eu^＊---1.59）, which reveals its hydrothermal sedimentation origin and it may have formed in the environment of submarine exhalation.
基金Supported by the China National Science and Technology Major Project(2017ZX05063).
文摘Based on exploration and development results and evaluation of marine shale gas in South China in the past ten years, in view of the features of "high maturity, strong tectonic reformation and high shear stress" of the shale in Zhaotong exploration zone in the Yunnan and Guizhou Plateau, as well as the key issues of long time diffusion and leakage of shallow shale gas, and the preservation conditions, the factors controlling shallow shale gas sweet spot and key zone selection evaluation technology of shale gas are investigated. From 2017 to 2018, the first significant exploration breakthrough was made in the Taiyang anticline at a buried depth of 700 to 2 000 m, discovering large-scale proved geological reserves of shallow shale gas. By examining the accumulation conditions and sweet spot control factors of the shallow shale gas in this area, it is found that the accumulation and productivity potential of shale gas in the mountainous area with complex structure outside basin are controlled by five factors:(1) The gas-rich area has weak tectonic reformation and good preservation conditions on the whole, taking on typical anticline trap occurrence mode.(2) The gas-rich area is in over-pressure state and high in shale gas content.(3) The gas-rich area has high quality shale and thus superior source rock condition.(4) The gas-rich area has high quality reservoirs dominated by class I.(5) The shale gas reservoir in the gas-rich area has high content of brittle minerals and small difference between maximum and minimum horizontal stresses which are conducive to hydraulic fracturing. The innovative practice and core technologies formed during the exploration and production capacity construction of shallow shale gas in the Zhaotong demonstration zone have great reference significance for shallow shale gas exploration and development in other areas.
基金supported by the Research Institute Exploration and Development,PetroChina Yumen Oilfield Companythe National Natural Science Foundation of China(No.2011ZX05009-002)Open Project Foundation of Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education,China(No.TPR-2013-12)
文摘ABSTRACT： Yinger sag is the main petroleum and only the Changshaling oil resource has shaling anticline crest zone was formed above the generative sag in eastern Jiuquau Basin, been found after 60 years prospecting. Chang- regional uplift, and was slightly affected by crest was identified as a structural transposition zone. Based on analysis of seismic facies, logging facies and seismic inversion technique, it has been demonstrated that anticline crest zone conducts drainage entering basin and dominates sedimentary detritus further dispersing, and the anticline crest zone controls the distribution of sand bodies and the development of sedimentary system consequently. The sequence stratigraphic patterns of multi-step fault belt in Member 3 of Xiagou Formation in Lower Cretaceous in the anticline crest zone is composed of the development of sedimentary facies in plan and distribution of multi-step fault belt sand bodies in spa- tial. This research investigates the sand-control models and sequence patterns, and finally a model of reservoirs in anticline crest zone is identified.
基金supported by the National Natural Science Foundation of China(Grant No.U19B6003-01)。
文摘In this study,we aim to clarify the structural characteristics and deformation process of the Changning anticline.We carefully interpret 38 two-dimensional(2D)seismic profiles in the study area and establish three-dimensional(3D)geometric and quantitative kinematic models of the Changning anticline.This study shows that the basement fault controls the formation of the Changning anticline.The fault slope of the main fault in the basement shows’steep in the upper and gentle in the lower’structural characteristics vertically,possessing obvious segmentary characteristics transversely and presents the overall characteristics of’steep in the east and gentle in the west’.Further analysis shows that the Changning anticline proceeds west and terminates at the boundary defined by current surface features but gradually disappears westward across the Mt.Huaying fault zone.Furthermore,we identified that deformation of the Changning anticline began during the early Yanshanian movement period.Under compressional stress from the southeast,the anticline slid forward along the basement fault until the end of the Yanshanian movement period,when the dominant WNW-ESE structure gradually emerged.Since the Himalayan movement period,a series of NE-trending structures have been formed in the anticline,owing to multi-directional compressive stress.
文摘The study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin (175 km from Persian Gulf). The Zagros fold-thrust belt is home to one of the largest petroleum producing reservoirs in the world. Structures in this area have complications and the study anticline has unique structures in the Fars region. In the study area, the Kuh-e Qazi anticline due to special fold style and rotation toward Northeast is the unique structure between anticlines of the Zagros belt. This anticline is fault bend fold and plunge of the anticline in eastern part rotated toward Northeast along with the Nezamabad fault trend. In this area, the Kuh-e Qazi anticline has asymmetric structures and some faults such as the Nezamabad and the Sarvestan strike slip fault effect on this anticline. The geometry of anticlines in the Zagros fold-thrust belt is affected by the type of deformation and mechanical behavior of stratigraphic units specially detachment units. The purpose of this research is to determine of folding pattern of the Kuh-e Qazi anticline and define structural features affected on them in the study area. This paper presents a part of the results of a regional study of the Fars province in the Zagros Simply Folded Belt, based on original fieldwork, satellite images, structural sections, geological maps and well data. Also, we use some software as Global Mapper and Tectonics FP for preparing some data.?Based on the research, which have been done, the boundary between ductile and frictional substrates causes rotation as a result of lateral, along-strike migration of the ductile substrate. The ductile or viscose layer in the study area is Hormuz Series. Due to lack or thinning of Hormuz salt over the Gavbandi basement high and in the eastern side of the Nezamabad basement fault, causes translation of strain and anticlockwise rotation in Southeast of the Kuh-e Qazi anticline toward Northwest unlike foreland basin due to the Nezamabad fault activity. This style between all of the anticlines in the study area is unique that rotates unlike foreland basin. In addition, influence on anticlockwise rotation, extensional stress has been created and then salt dome cropping out in Southeast of the Kuh-Qazi anticline. One of the best evidence for effect of extensional stress is triangular facets in this part of the study anticline. Based on folding analysis (geometry of axial plane and fold orientation), it is clearly confirmed that the translation of strain and anticlockwise rotation in Southeast of the Kuh-e Qazi anticline toward Northwest has been formed by basement fault activity as the Nezamabad fault in the boundary between ductile and frictional substrates of the study area.
基金Supported by the China National Science and Technology Major Project(2016ZX05060001-032)
文摘The main area of the Jiaoshiba anticline of the Fuling shale gas field was taken as the research object,laboratory rock mechanical experiments and direct shear experiments were conducted to clarify the mechanical anisotropy characteristics and parameters of rock samples with rich beddings.Based on the experimental results,a 3D fracture propagation model of the target reservoir taking mechanical anisotropy,weak bedding plane and vertical stress difference into account was established by the discrete element method to analyze distribution patterns of hydraulic fractures under different bedding densities,mechanical properties,and fracturing engineering parameters(including perforation clusters,injection rates and fracturing fluid viscosity).The research results show that considering the influence of the weak bedding plane and longitudinal stress difference,the interlayer stress difference 3–4 MPa in the study area can control the fracture height within the zone of stress barrier,and the fracture height is less than 40 m.If the influence of the weak bedding plane is not considered,the simulation result of fracture height is obviously higher.Although the opening of high-density bedding fractures increases the complexity of hydraulic fractures,it significantly limited the propagation of fracture height.By reducing the number of clusters,increasing the injection rate,and increasing the volume and proportion of high-viscosity fracturing fluid in the pad stage,the restriction on fracture height due to the bedding plane and vertical stress difference can be reduced,and the longitudinal propagation of fractures can be promoted.The fracture propagation model was used to simulate one stage of Well A in Fuling shale gas field,and the simulation results were consistent with the micro-seismic monitoring results.
基金Supported by the National Natural Science Foundation of China(41430316,40739906,41272237).
文摘Hydraulic fracturing is a key technology in shale gas extraction,whether hydraulic fracturing induces earthquakes has become a hot topic in the public and the focus of scholars’research.The urgency of shale gas mining and the catastrophic nature of earthquakes highlight the urgent need to study this issue.The Changning anticline at the southern margin of the Sichuan Basin is a key area for shale gas exploitation.Taking this as an example,this paper applies the velocity model of the study area to reposition the M5.7 magnitude earthquake on December 16,2018 and the M5.3 magnitude earthquake on January 03,2019 and their aftershock sequence in this area.Using shale gas exploration drilling and reflection seismic data to carry out structural analysis,and recovering the tectonic geological setting of earthquake occurrence by restoring the formation process of the Changning anticline,to further explore the seismic mechanism.Our results show that the Changning anticline is a large basement fault-bend fold,and the displacement of the fault forming the anticline is 18 km,and the Changning anticline absorbs 33%of the fault slip.The Silurian Longmaxi Formation of the Changning anticline experienced larger-parallel shearing along underlying basement faults,forming a micro-fracture system.The footwall ramp of the basement fault is reactivated at present,earthquakes in this area mostly occur along the footwall ramp of the basement fault and above and below it.The anticlinal and synclinal hinge zones are also the earthquake concentration areas,but the earthquake magnitude decreases upwards along the kink-band,and small earthquakes below M2.0 occur in the Silurian Longmaxi Formation.So far,the earthquake in the Changning anticline mainly occurred in the southern limb of the anticline,which is a natural earthquake formed along the footwall ramp of the basement fault.The earthquakes in the Changning area are possible related to the geo-tectonic setting for the southeast outward compression of the Qinghai-Tibet Plateau at present,the moderate or large-scale earthquakes in the southwest Sichuan Basin are mainly due to the reactivation during late Quaternary of the earlier formed faults.It is suggested to carry out scientific monitoring of seismic activities in shale gas development zones.
文摘The Kuh-e Siah anticline is located in the Sarvestan area of the Fars province (186 km to Persian Gulf) and Interior Fars sub basin. This anticline is a fault bend fold and is located in the Sarvestan fault zone with Northwest-Southeast trend. The Sarvestan fault zone has caused main deformation by dextral strike slip activity in southern part of the Zagros fold-thrust belt. The main aim of this paper is to determine of fold style elements and folding pattern of the Kuh-e Siah anticline. This paper presents part of the results of a regional study of the Fars province in the Zagros Simply folded belt, based on original fieldwork, satellite images, structural sections, geological maps and well data. In addition, we used some software as Global Mapper and Tectonics FP for prepared some data. Folds, which are close sideways, are neutral and these require special attention. It is remarkable that, in all sections of the Kuh-e Siah anticline, fold type is close and in the middle part of the anticline, fold type is different with other parts. In the middle part, fold type is upright-moderately gently plunging. On the other hand, in northwestern and southeastern parts fold type is similar together. These results maybe show that fold style follow that fold sigmoidal shape that created with two-fault segment of the Sarvestan fault zone in the study area. Therefore, it seems that the Kuh-e Siah anticline has suffered high deformation in the Sarvestan fault zone and this fault zone has created shear zone.
文摘The Study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin. The Khaftar anticline is located in the West, North-West of Jahrom city in the Fars province (148 km distance from Persian Gulf). The trend of Khaftar anticline has three orientations, consist of North-Northeast, East-West and South-Southwest. This anticline has asymmetric structure and some faults with large strike separation observed in this anticline. In the study area, stratigraphic units are affected by many faults in this area. Also one salt plug cropping out in the middle part of the Khaftar anticline. Maybe this salt plug affected on the stratigraphic units and geometry of structure. Description of fold geometry is important because it allows comparisons within and between folds and allow us to recognize patterns in the occurrence and distribution of fold systems. The main aim of this paper is determination of fold style elements and folding pattern of the Khaftar anticline. This paper presents a part of the results of a regional study of the Fars province in the Zagros Simply folded belt, based on satellite images, geological maps, and well data. Some data, such as geological maps and geological regional data were prepared and provided by the National Iranian Oil Company (NIOC). Because of the Khaftar anticline, has complex structure, the analysis of fold style elements is seems necessary. Therefore, in further studies on this structure the changes of fold style elements will be analyzed and investigated from east to west in the different parts of this anticline. The activity of Nezamabad sinistral strike slip fault in the Khaftar anticline causes changes of axial plane characteristics and fold axis. Some of the results such as folding style analysis, how position of salt plug, changes of fold type and main structural changes (rotation of fold axis and 2.5 km displacement in this anticline) show main changes in the middle parts of the Khaftar anticline. It seems that, these changes have formed by activity of the Nezamabad fault and this fault’s activity same as fault zone.
文摘The Khalfani anticline is located in the Coastal Fars (Zagros, adjacent Persian Gulf). This anticline with Northwest-Southeast trend is a fault bend fold. In the study area, the Khalfani anticline has increased elevation from West to East with three distinct humps. The major faults in the study area are the Hendurabi and the Razak sinistral strike slip faults. Because analysis of fold and their folding styles in different parts system is important, the analysis of folding style elements is necessary for structural studies. The main aim of this research is structural style analysis based on fold style elements in the Khalfani anticline. This analysis is important for progress in hydrocarbons exploration in the Coastal Fars area. In this research, we used Tectonics FP and Global Mapper Software for preparing some data in our study. In addition, we used the common classification of folds for our research. Based on given results, the folding pattern of this anticline has indicated that the fold style is same in different parts of the Khalfani anticline. In the study area, based on classifications of fold in different methods, fold style is same together. Fold, with close sideways requires special attention as structural view;then the Khalfani Anticline with close style in all parts has special deformation and folding style. It seems that in the study area, folding style and variation of structural style have been created by effect of the Razak and the Hendurabi sinistral strike slip fault. Because these faults are basement or deep-seated faults, special folding style and special deformation can be formed in the study area. In addition, the Khalfani anticline in the study area has restricted within the Razak and the Hendurabi sinistral strike slip faults.
文摘The Gavbast anticline is located in the Coastal Fars area of the Zagros folded belt, with north-south trend. The study anticline is restricted to the Bavush and Paskhand anticlines from North, the Gezzeh and Dehnow anticlines from South, the Varavi anticline from West and Nakh anticline from East (Figure 1). Description of fold geometry is important because they allow comparisons within and between folds and pattern-recognition in addition to occurrence and distribution of fold systems. The main goal of this paper is to define folding style of the Gavbast anticline and define structural features affected on them in the study area. In this research, we used the Tectonics FP software, Global Mapper software and geological maps and reports of Iranian National Oil Company. In addition, we used common classification of fold for indicating of folding mechanism of the Tabnak anticlinal structure. In the Gavbast anticline, fold style elements in all parts of this anticline have been calculated and analyzed for indicating of folding style mechanism. The results of this method have been shown the folding geometry changes accurately. The Gavbast anticline is gentle in structural sections D-D' and G-G' to K-K'. The anticline is an open fold in the L-L' section. Also fold type in the E-E' and F-F' sections of the Gavbast anticline is steeply inclined sub-horizontal. These sections are located between the Razak (western part) and Hendurabi fault (eastern part). It seems that E-E' and F-F' parts in the Gavbast anticline have been suffered most deformation affected by the Razak and Hendurabi faults. At the end of, it seems that, the Razak and Hendurabi faults have major effects on folding style. This structure is a very good sample for effect of strike slip faults on the folding geometry and for this reason;the Gavbast anticline is considered a special structural style in the Zagros fold-thrust Belt.
基金funded by the China Geological Survey Bureau of the Western Region in potassium mineral prospect survey evaluation (No.DD20160054)the Sichuan Provincial Geological Prospecting Fund Project (Huangjinkou potash general survey, Xuanhan County, Sichuan Province)the China Postdoctoral Science Fund (No. 2017M620885)
文摘Objectives Important clues have been found for potassium prospecting in the Huangjinkou anticline of the northeast Sichuan Basin in the 1970s(Zheng et al.,2015;Lin et al.,2004).In 2008,China Geological Survey launched a prospective investigation of potash resources in the western region of China,and the local governments and private-owned enterprises also responded positively.Then,
